Deciphering the Structural, Textural, and Electrochemical Properties of Activated BN-Doped Spherical Carbons

Bridget K Mutuma; Boitumelo J Matsoso; Damilola Momodu; Kabir O Oyedotun; Neil J Coville; Ncholu Manyala

doi:10.3390/nano9030446

Deciphering the Structural, Textural, and Electrochemical Properties of Activated BN-Doped Spherical Carbons

Nanomaterials (Basel). 2019 Mar 16;9(3):446. doi: 10.3390/nano9030446.

Authors

Bridget K Mutuma^{1

2}, Boitumelo J Matsoso³, Damilola Momodu⁴, Kabir O Oyedotun⁵, Neil J Coville⁶, Ncholu Manyala⁷

Affiliations

¹ Department of Physics, Institute of Applied Materials, SARChI Chair in Carbon Technology and Materials, University of Pretoria, 0028 Pretoria, South Africa. bridgetmutuma@gmail.com.
² Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, 2050 Johannesburg, South Africa. bridgetmutuma@gmail.com.
³ Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, 2050 Johannesburg, South Africa. boijo.matsoso@gmail.com.
⁴ Department of Physics, Institute of Applied Materials, SARChI Chair in Carbon Technology and Materials, University of Pretoria, 0028 Pretoria, South Africa. dymomodu@yahoo.com.
⁵ Department of Physics, Institute of Applied Materials, SARChI Chair in Carbon Technology and Materials, University of Pretoria, 0028 Pretoria, South Africa. kabir.oyedotun@gmail.com.
⁶ Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, 2050 Johannesburg, South Africa. neil.coville@wits.ac.za.
⁷ Department of Physics, Institute of Applied Materials, SARChI Chair in Carbon Technology and Materials, University of Pretoria, 0028 Pretoria, South Africa. ncholu.manyala@up.ac.za.

Abstract

In this study, the effect of K₂CO₃ activation on the structural, textural, and electrochemical properties of carbon spheres (CSs) and boron and nitrogen co-doped carbon spheres (BN-CSs) was evaluated. Activation of the CSs and BN-CSs by K₂CO₃ resulted in increased specific surface areas and I_D/I_G ratios. From the X-ray photoelectron spectroscopy (XPS) results, the BN-CSs comprised of 64% pyridinic-N, 24% pyrrolic-N and 7% graphitic-N whereas the activated BN-CSs had 19% pyridinic-N, 40% pyrrolic-N and 22% graphitic-N displaying the effect of activation on the type of N configurations in BN-CSs. A possible BN-co-doping and activation mechanism for the BN-CSs is proposed. Electrochemical analysis of the electrode materials revealed that BN doping, carbon morphology, structure, and porosity played a crucial role in enhancing the capacitive behavior of the CSs. As a proof of concept, a symmetric device comprising the activated BN-CSs displayed a specific power of 800 W kg^-1 at a specific current of 1 A g^-1 within an operating cell potential of 1.6 V in a 3 M KNO₃ electrolyte. The study illustrated for the first time the role of K₂CO₃ activation in influencing the physical and surface properties of template-free activated BN-CSs as potential electrode materials for energy storage systems.

Keywords: activation; boron and nitrogen co-doped carbons; carbon spheres; supercapacitor.

Grants and funding

61056/National Research Foundation